SIG Sauer unveiled a new medium machine gun (MMG) chambered for the .338 Norma Magnum cartridge at this year's Association of the US Army symposium (AUSA), held in Washington, DC, from 8 to 10 October.

The weapon is thought to be a direct competitor to the General Dynamics Ordnance and Tactical Systems Lightweight Medium Machine Gun chambered for the same round.

The exact system of operation of the latest SIG Sauer MMG is unknown, but Jane's believes that it is probably gas cycled. Company representatives who spoke to Jane's at AUSA were unwilling to reveal any particular details regarding the weapon, claiming that its system is "unique and novel".

On display at the show next to the MMG was a new kind of .338 Norma Magnum (NM) ammunition. SIG Sauer representatives were again unwilling to disclose any particular details, although one executive did confirm to Jane's that the casings of the new .338 NM cartridge are made of polymer to reduce the overall weight of the round, with a 'steel head' at the base.

Jane's understands the new MMG prototype has an approximate effective range of 2,000 m, weighs under 20 lb (9.1 kg) unloaded, and is in the early stages of development.

The weapon on display was not fitted with a bipod. It featured a Bravo left-side folding telescopic butt of the M4 carbine series style made by B5 Systems, a folding charging handle on the right-hand side of the receiver, and an ambidextrous safety lever positioned on the receiver, above the pistol grip.

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